How has the respiratory system evolved in animals?

Evolutionary Web

In conclusion, the respiratory system has evolved to meet the needs of each organisms environment. The lungs are estimated to have originated 375 million years ago, derived from the swim bladder that is used in many fish to control their buoyancy. The transition from aquatic respiration to land-dwelling respiration was a huge step in our evolution and required many physiological and anatomical changes. The respiratory system evolved along with components of the circulatory system. The presence of lungs required a more complicated "double circuit" system of blood circulation to bring oxygenated blood to the tissues and deoxygenated blood back to the heart and lungs. Changes in both of these systems lead to the respiratory diversity we see today within the animal kingdom.

How does each animal respire?

Snail : The presence of lungs or gills on a snail ultimately determines in what kind of environment they are capable of living. This respiratory variation within the snail species accommodates their astonishing diversity.

Octopus : They do not have lungs. Instead, octopi use gills, a mantle, epidermis and a siphon to respire under the water.

Frog: Throughout their life cycle, frogs are able to respire with gills, lungs, through their skin and through specialized membranes.

Cheetah: Respiration is much like humans only, due to enhanced oxygen needs, cheetahs have enlarged nostrils, sinuses, lungs and heart to deliver oxygen more rapidly.

Eagle: the specialized system of air sacs helps to ensure birds only utilize fresh oxygen and keep their lungs filled with air at all times.

Whale: Although their respiratory system is very similar to land mammals, they utilize myoglobin, collapsing lungs, and bradycardia in order to survive underwater for long periods of time.

As shown above, animals have their own unique respiratory systems based on the environment they live in. Living in aquatic environments often requires an animal to have gills. However, as we see in the whale and octopus, this is not always the case. Even on land, where oxygen is more readily available, animals have developed very different respiratory systems.

Why does it matter?

Respiration is a physiological process necessary for the survival of many organisms. It generally involves the intake of oxygen and the expelling of carbon dioxide.